<!DOCTYPE html>
<html>
    <head>
        <title>TODO supply a title</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <style>
            /*.container > section p {*/
            #b001 {
                position: relative;
                z-index: 1;
                /*outline: 1px red dashed;*/
            }
            .color-1 {
                /*background: #0e83cd;*/
                background: lightgrey;
            }
            .btn {
                background: none;
                cursor: pointer;
                padding: 25px 80px;
                display: inline-block;
                margin: 15px 30px;
                text-transform: uppercase;
                letter-spacing: 1px;
                font-weight: 700;
                outline: none;
                position: relative;
                border: 3px solid #fff;
                color: #fff;
            }

            .btn:before {
                content: '';
                position: absolute;
                z-index: -1;
                -webkit-transition: all 0.6s;
                -moz-transition: all 0.6s;
                transition: all 0.6s;
                /*a*/
                width: 100%;
                height: 0%;
                top: 100%;
                left: 0;
                background: #fff;
                /*background: red;*/
                /*a*/
            }

            /* Pseudo elements for icons */

            .btn:hover,
            .btn:active {
                color: #0e83cd;
                /*color: red;*/
            }

            .btn:hover:before,
            .btn:active:before {
                height: 100%;
                width: 100%;
                top:0%;
            }
        </style>
        <!--<link rel="stylesheet" type="text/css" href="css/a001_b01_01.css" />-->
        <!--<link rel="stylesheet" type="text/css" href="css/a001_b01_02.css" />-->
    </head>
    <body>  
        <div class="container">
            <section class="color-1">
                <p id="b001">
                    <button class="btn">Button</button>
                </p>
            </section>
        </div>
    </body>
</html>
